High voltage and high current pulse generator in combination with field emission type x-ray tube



June 14, 1966 w. P. DYKE ETAL 3,256,439

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN UOMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17. 1962 8 Sheets-Sheet l w "I 1 n I I 1 44 '5 l I V I! .24 l @9 i 5? 36 258 Y m 1 5 a "4 k 2 m J I 1 Fig.

l/WENTORS. WALTER e um" FRANK a. mama/140559 NORMA/V M STUN/(ARD er BUCKHORN, BLORE, KLAROU/ET 8 SPAR/(MAN AT TORNE YS June 14, 1966 w. P. DYKE ETAL 3,256,439

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17, 1962 8 Sheets-Sheet 2 FRANK J. GRU/VDHAUSER NORMA/V W STUNKARD B) BUCKHOEW, BLORE; KLAROU/S 7' 8 SPAR/(MAN AT TORNE YS June 14, 1966 w. P. DYKE ETAL 3,256,439

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17, 1962 8 Sheets-Sheet 3 ATTORNEYS BUG/(HORN, BLORE, KLAROU/ST 8 SH IRKMA/V June 14, 1966 w. P. DYKE ETAL 3,256,439

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17, 1962 8 Sheets-Sheet 4 WALTER DY/(E' FRANK J. GRU/VD/IAUSER By NORMA/V WSTUN/(ARD BUC/(HORN, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS June 14 1966 W. P. D

HIGH VOLTAGE AND al gn na imw PULSE 3256439 GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17, 1962 a Sheets-Sheet s I/VVENTORS.

WALTER DY/(E F RANK J. GRUA/DHAUSER NORMAN I. STUNKARD BUG/(HORN, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS June 14, 1966 w. P. DYKE ETAL 3, 56, 9

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE 8 Sheets-Sheet 6 Filed Dec. 17, 1962 4 5 my R w W m TMDN m ww V M8 W w RJ. .0 M H 8 W 9 2 .Q. I F

BUG/(HORN, BLORE, KLAHOU/ST 8 SPAR/(MAN AT TORNE Y3 June 14, 1966 Filed Dec. 17, 1962 W. P. DYKE ETAL HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE 8 Sheets-Sheet 7 INPUT MODULE 52 MODULE NO. 2 /42 ADDITIONAL MODULES IDENTICAL TO MODULE N0. 2

Fig. /3

INVENTORS.

WALTER P DYKE FRANK I1 GRUNDHAUSER NORMA/V Ml STU/ KARO TRIGGER I INPUT 5r BUG/(HORN, BLORE, KLAROU/ST a SPAR/(MAN ATTOR/VfYS June 14, 1966 w. P. DYKE ETAL 3,256,439

HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Filed Dec. 17, 1962 8 Sheets-Sheet 8 B) RUE/(HORN, BLORE; KLAROU/S 7' 8 SPAR/(MAN ATTORNEYS United States Patent HIGH VOLTAGE AND HIGH CURRENT PULSE GENERATOR IN COMBINATION WITH FIELD EMISSION TYPE X-RAY TUBE Walter P. Dyke and Frank J. Grundhauser, McMinnville, and Norman W. Stunkard, Oswego, 0reg., assignors to Field Emission Corporation, McMinnville, 0reg., a corporation of Oregon Filed Dec. 17, 1962, Ser. No. 245,182 Claims. (Cl. 250-98) This invention relates to an X-ray unit and to a high energy electrical pulse generator employed in such X-ray unit, as well as to a charge storage module used by such electrical pulse generator. The present invention relates more particularly to .an X-ray unit which may be of small size so as to be readily portable and which will produce one or a series of short pulses of high intensity X-rays, each containing the same amount of X-ray radiation so that the total exposure or dosage can be accurately controlled in a simple manner.

The X-ray unit of the present invention includes a high voltage pulse generator having a plurality of charge storage modules of generally plate-like form each containing -at least one transmission line section which can be charged to a high voltage. Thus the modules may be of circular or rectangular shape in plan and have opposed major surrfaces oi considerably greater dimensions than the thickness of the modules. The modules are positioned so as to be stacked with their major surfiaces adjacent each other and connections embedded in such surfaces connect the transmission linesections together through isolating impedances which allow the sections to be charged in parallel with DC. but to prevent short oircuiting of short high voltage pulses produced by discharging the transmission line sections in series.

Each module contains a spark gap for connecting the transmission line sections in series when the spark gaps break down. The spark gaps are positioned in recesses in the modules so as to be in alignment and be exposed to each other. The modules are held in alignment by being positioned in a casing and the casing may be closed so as to provide for maintaining a gas under pressure in the casing. The gas in the triggered spark gap emits ultraviolet light when it is ionized and this light is transmit-ted to the remaining spark gaps substantially instantaneously to cause the breakdown of such remaining spark gaps at approximately the same time in the manner described in copending US. patent application, Serial No. 103,796, filed by W. P. Dyke et al. on April 18, 1961, and entitled High Voltage Pulser. The various elements of the modules themselves are immersed or potted in dielectric material such as synthetic resins having high dielectric strength so that premature sparking or flashover within the modules themselves is largely prevented. The gas pressure in the casing, however, increases the voltage to which the transmission line sections may be charged without undesired premature discharge or arcing between exposed conductors on the surfaces of the modules. The positive gas pressure also isolates the interior of the pulser from atmospheric effects by preventing the entrance of moisture, dust, etc. In case of failure of any module,

however, the casing can be readily opened and a new module substituted for the defective module.

The casing also preferably has provision for supporting and housing an X-ray tube of a type which can be energized by high voltage, high current electrical pulses. The tube may thus be positioned in a tube extending through aligned apertures in the modules or a separate housing forming part of the casing structure can be employed. Provision is also preferably made for positioning the tube at the end of a suitable cable so that the tube can be brought closer to the object to be X-rayed in cases where the casing is inconveniently large.

The X-ray uni-t also includes a charging and control circuit which enables charging of the transmission line sections to a predetermined high voltage and also enables triggering of the operation of the spark gaps to provide the high voltage, high our-rent pulses referred to above. Such control circuit preferably enables a predetermined and presettable number of such pulses to be produced in rapid succession.

It is therefore an object of the present invention to provide an improved X-ray unit which may be portable and of small size.

Another object of the invention is to provide an X-ray unit in which a plurality of modules each containing a transmission line section capable of being charged to a high voltage are held in a compact stacked arrangement.

An additional object of the present invention is to provide an improved electrical pulse generator which produces narrow, rectangular pulses of high voltage and current and of short rise time by causing a plurality of spark gaps to break down at substantially the same time to discharge a plurality of storage modules in series.

Another object of the invention isto provide an X-ray unit in which a plurality of modules for storing electricity at high voltage are held securely in a casing which also forms a housing for an X-ray tube capable of producing intense pulses of X-rays of short duration when said modules are discharged in series through said tube.

Still another object of the present invention is to provide a charge storage module of small size and rugged construction which contains an artificial transmission line of substantially uniform characteristic impedance con nected to spark gap electrodes attached to such module.

A further object of the invention is to provide an X-ray unit capable of producing a series of intense pulses of X-ray radiation, each having a predetermined amount of such radiation, in rapid succession and in which the number of pulses thereby produced is predetermined and presettable in order to accurately control the total X-ray radiation or dosage.

Other objects and advantages of the invention will appear in the following description of embodiments thereof shown in the attached drawing of which:

FIG. 1 is a perspective view of the rear of an X-ray unit in accordance with the present invention with the rear cover removed;

FIG. 2 is a side elevation of an assembly forming part of the unit of FIG. .1, including a casing containing electricity storage modules provided with spark gaps and housing an X-ray tube, with parts of the casing broken away to show certain or the modules;

FIG. 3 is a plan view of the assembly of FIG. 2 with parts broken away to show internal contents and structure and with the housed X-ray tube shown in longitudinal section;

FIG. 4 is a side elevation of the plug end of a plug, cable and tube assembly by which the X-ray tube can be employed at a distance from the X-ray unit of FIG. 1;

FIG. 5 is a plan view of one of the modules of the assembly of FIGS. 2 and 3 with the potting material largely omitted to show the internal arrangement of elements;

FIG. 6 is a front elevation of the module of FIG. 4

with internal parts shown in dotted lines;

FIG. 7 is an isometric exploded view showing certain of the modules and a closure structure of the casing for the modules;

FIG. 8 is an isometric view of a triggering module showing the triggering electrode;

FIG. 9 is a perspective view of the unit of FIG. 1 with the rear cover removed and the plug, cable and tube assembly partly shown in FIG. 4 plugged into the unit;

FIG. 10 is a longitudinal section through the casing of a modified assembly of electricity storage modules and an X-ray tube positioned in a casing with portions of the modules shown in side elevation and other portions of the modules broken away;

FIG. 11 is a plan view of one of the modules of FIG.

10 on an enlarged scale with potting material omitted to show the arrangement of internal parts; FIG. 12 is a side elevation of two of the modules of FIG. 11 with parts broken away and sectioned so that such parts are viewed in section approximately on the line 12-12 of FIG. 11;

FIG. 13 is a schematic diagram showing the connections of the modules and the X-ray tube; and

FIG. 14 is a schematic diagram showing a control circuit for an X-ray unit capable of providing a preset number of high intensity X-ray pulses in rapid succession.

Referring more particularly to FIG. 1 of the'drawings, the X-ray unit of FIG. 1 includes a carrying case showing as having a carrying handle 22. The rear cover (not shown) has been removed from the carrying case to show that such case contains an electricity storage and X-ray tube assembly 24 which as shown in FIG. 3, includes a casing 26 of insulating material containing a plurality of electricity storage and spark gap modules 28 and another similar module 29 modified for performing a triggering operation. The assembly also includes an X-ray tube 30, a trigger transformer 32 and a desiccant element 34.

The carrying case 20 of FIG. 1 also contains a control assembly 36 containing the control and high voltage'supply circuit of FIG. 14. It will be understood that the carrying case 20 of FIG. 1 will also have a front panel (not shown) through which extend from the control unit, the various control shafts and push button controls indicated diagrammatically in FIG. 14. It will also be understood that such front panel will have various control -indicia thereon in a manner conventional with electric or electronic instruments.

As shown in FIGS. 2 and 3, the modules 28 and 29 are housed in the main body portion of the casing 26 of the assembly 24 and the X-ray tube and desiccant element 34 are positioned in separate housings 38 and 40, respectively, integral with and carried by the casing 26. The desiccant element 34 may be of any suitable material such as silica gel, and the housing 40 therefor has a slot 42 in the wall between such housing and the main body portion of the casing 26 containing the modules 28 and 29 so that water vapor can reach the desiccant element. The desiccant element is held in the housing 40 by a screw cap 44 in the rear end of the housing 40.

The X-ray tube 30 is held in its housing 38 by a cap 46 received within the open end of such housing and held therein by a bayonet joint including screws 48 secured in the cap and received in an inclined slot 50 in a tubular metal insert 52 forming part of the housing 38. The cap 46 has a thin window 54 in its end for X-rays. The X-ray tube has a metal cup-shaped end portion 56 secured to a metallic annular member 58 which is sealed to the glass envelope 60 of the tube and which provides a radially extending flange engaged between the cap 46 and metal insert 52 of the housing 38 to hold the tube in position. Such metal insert 52 also has a ring of spring fingers 62 extending longitudinally of the tube and engaging the annular member 58 to provide effective electric contact with such annular member. The cup-shaped member 56 for the tube is also provided with a thin metallic window 64 for X-rays.

The annular member 58 also provides an internal flange forming a support for a cathode structure 66 of the type disclosed in the copending application of Dyke and Grund'hauser, Serial No. 114,125, filed June 1, 1961,

now US. Patent 3,174,043. The cathode structure includes a plurality of blocks of metal arranged circumferentially of the tube and each provided with a plurality of metallic needle points 68 directed radially inwardly of the tube. Such needle carrying blocks are supported in a tubular shielding and electron focusing metal member 70 in turn supported on and in axial alignment with the annular member 58. A suitable metal for the needle points is tungsten and the annular member 58 should be of a metal alloy having substantially the same thermal coefficient of expansion as the glass of the envelope 60.

A conical anode element 72 is positioned centrally of the tube between the needle points 68 and also may be of tungsten. It is supported on a lead 74 so that its pointed end is directed toward the windows 64 and 54. When a high voltage, high current electron pulse discharge is produced between certain of the needle points 68 and the anode element 72 by field emission and vacuum arc operation, an intense pulse of X-ray radiation is transmitted through the windows 64 and 54.

The anode lead 74 is sealed through a press in a reentrant portion 76 in the glass envelope 60. The exterior end of such lead is received in a socket member 78 forming part of a metallic telescopic assembly 80 containing a compression spring 82 which expands the telescopic as sembly between the anode lead 74 and a metallic connector element 84 molded into the end of the housing 38 remote from the cap 46. The connector element has a conductor 85 leading to the interior of the casing 26 for connection to the modules 28 and it will be understood that a suitable conductor (not shown) leads to the metallic insert 52 of the tube housing 38. The spring 82 urges the X-ray tube toward the cap 46 of the housing 38 to hold it resiliently in position.

The casing 26 for the modules is closed at one end and has a closure structure 86 at its end adjacent the cap 46 for'the tube housing 38. Such closure structure is most clearly shown in FIG. 7 and includes a molded block of insulating material having a housing '88 for the trigger transformer 32 (FIG. 3) molded integrally therewith. The closure structure 86 has connectors 90 and 92 (FIG. 7) for connection to coaxial cables 94 and 96 (FIG. 1), respectively, leading from the high voltage supply and trigger control, respectively, of the control assembly 36. As will be clear from the circuit diagram later described, the connector 90 (FIG. 7) has its inner conductor connected internally of the closure structure to a spring contact 98 which projects from the closure structure toward one of the modules 28 and the connector 92 has its inner conductor connected internally to one of the connectors 100 (FIG. 3) for the trigger transformer 32. One of the other trigger transformer connectors 100 is connected to a spring trigger contact 102 (FIG. 7) and the remaining connector 100 is connected to the outer conductor of the connector 92. Such outer conductor of connector 92 is also connected to the outer conductor of the connector 90 and to a spring contact 104 similar to the spring contact 98, as well as to a banana plug connector 106 which is received in a socket (not shown) in the main body of the casing 26 and is connected to the metal insert 52 (FIG. 3) of the tube housing 38 so as to be in turn connected to the cathode structure of the tube 30.

The closure structure 86 is held in position on the open end of the body of the casing 26 by screws 108 (FIG. 1) extending through suitable holes in the closure structure to form a gas tight enclosure. This positions the housing 88 for the trigger transformer 32 as shown in FIGS. 1 and 3. The transformer 32 is a replaceable plug in element held in position by a screw cap 110 closing the transformer housing 88. The closure structure 86 also has a tube connector 112 to which a tube 114 (FIG. 1) leading from the control assembly 36 is connected. Such control assembly contains a small hand operated air pump (not shown) and a visible pressure gauge (also not shown) so that air under a definite pressure can. fi .up

plied through the tube 114. The connector 112 communicates with an aperture 115 on the inner surface of the closure structure 86 so that the air pressure in the interior of the casing 26 can be increased to a desired pressure above'atmospheric pressure.

The modules 28 are all similar and are rectangular plate-like members and each have four contact elements 116, 118, 120 and 122. The contact elements 116 and 118 project from the major surfaces of the modules which are directed toward the end of the casing 2-6 having closure structure 86. The contact elements 128 and 122 form the lower surfaces of circular recesses in the other major surfaces of the modules and are in alignment with the contact elements 116 and 118, respectively, of an ad jacent module. The module 29 adjacent the closure structure is similar to the modules 28 except that it has a trigger electrode 123 supported in a web 124 as shown in FIG. 8. The trigger electrode extends through such web in position to be contacted by the spring contact 102 of FIG. 7. Otherwise the module 29 has the same structure as the other modules 28. It will be apparent that the contact elements 116 and 118 of the module 29 will engage the spring contacts 184 and 98, respectively, and that the contact elements 118 and 122 of each of the modules 28 and 29 constitute the DC. high voltage or charging connections and the contact elements 116 and 120- the low voltage or DC ground connections. The contact elements 120 and 122 of the intermediate modules 28 in the stack make electrical contact with contact elements 116 and 118, respectively, of adjacent modules through connector springs 125 and the contact element 122 of the module 28 farthest from the closure structure 86 makes contact with a suitable spring contact (not shown) connected to the conductor 85 (FIG. 3) leading to the anode connector 84 for the tube 30. The closure structure 86 holds the modules in position with the springs 125 compressed. Circular recesses 126 similar to and positioned on the same surfaces of the modules as the recesses associated with the contact elements 120 and 122 align with circular projections 127 (FIG. 6) to provide a third point of engagement between adjacent modules. It will be apparent that the projection 127 on the trigger module 2 9 will rest on the surface of theclosure structure 86 adjacent the module 29.

As shown in FIGS. 5, 6 and 13, each module 28 and 29 includes four high voltage capacitors 128 having one terminal of each connected to a common support and conductor plate 130 and their other terminals connected to spaced points on a coil to provide individual inductors 132 between such terminals with the inductors in series. A pair of spaced spark gap balls 134 and 136 are adjust-ably supported in a recess 138 in an edge of each module 28 and a similar recess 139 in the module 29. One end of the series of inductors 132 is connected through another small inductor 140 to the spark gap ball 136 and to the contact element 122. Such contact element is connected through a larger isolating inductor 142 to the contact element 118. The conductor plate 130 is connected directly to the contact element 116 and through another isolating inductor 144 to the other spark gap ball 134 and to the contact element 128.

It is noted that the spark gaps provided by the balls 134 and 136 are in alignment and exposed to each other so that ultraviolet radiation emitted from the ionized gas in the triggered spark gap will cause ionization and rapid breaking down of the other spark gaps. The recess 138 in the modules 28 is, however, partly closed along one side by a notched web or flange 146 and the recess 139 in the module 29 is completely closed along one side by the web 124 toprovide a longer path for surface leakage of current between points of high voltage on the surfaces of the modules. It will be understood that the modules are solid blocks of cast insulating material with the various elements described above potted or embedded therein.

It will be recognized that the capacitors 128 and induc- 6 tors 132 and of each module form an artificial transmission line of substantially uniform characteristic impedance which can be charged and which will deliver a short substantially squarewave of high voltage, high current electrical energy upon discharge. The inductors 148 and 144 allow the transmission lines to be charged with DC. in parallel and to be discharged in series when the spark gaps fire due to a triggering spark produced between the triggering electrode 123 and a spark gap ball 134.

The cap 46, tube 30 and telescoping spring connector assembly 88 can be removed from the tube housing 38 of FIG. 3 and the connector assembly 148 of FIG. 4 substituted therefor. The connector assembly includes a substitute cap 150 which replaces the cap 46 of FIG. 3 and connects to the tubular metal insert 52 of such figure and to the outer conductor of a coaxial cable 152. The connector assembly 148 also includes a banana plug connector received in the connector element 84 of FIG. 3

connected to the conductor 85. A

As shown in FIG. 9 the other end of the cable 152 may be connected to a tube housing 156 which may have internal structure essentially similar to the tube housing 38 of FIG. 3 and contain an X-ray tube 30. The outer conductor of the cable 152 is connected to a metal liner for the housing 156, similar to the metal insert 52 of FIG. 3, and the inner conductor of such cable is connected to a connector element similar to the connector element 84. The tube may thus be operated at a distance from the remainder of the unit although the pulse voltage will, in general, be lower than that possible when the tube is in the housing 38 of FIG. 3 because of cable insulation limitations.

The control circuit and high voltage supply circuit contained in the assembly 36 is shown in FIG. 14 and includes a power input 158 from a conventional 115 Volt 60 cycle line. One side 159 of the line contains a fuse 160 and is connected to stepping relay contacts 162 which in conjunction with a stepped rotor 164 having a continuous contact except for a notch and another contact 166 breaks the circuit when the notch is opposite the contact 166. The rotor can be manually turned clockwise in FIG. 14 a predetermined number of steps and, each time the actuating coil 168 of the stepping relay is energized, the rotor is moved one step in a counterclockwise direction until the circuit is broken. There also are norm-ally closed pressure safety relay contacts 170 in series with the side 159 of the 115 volt line, which contacts will not remain closed unless a pressure actuated switch 172 is opened due to pressure in the casing 26 (FIG. 3) for the modules 28. As long as the switch 172 remains closed the relay contact 170 vibrates between i an open and closed position as will be apparent from the following description of the circuit, but the high voltage supply is not energized since a high voltage power relay cannot be operated under these conditions.

Assuming that the pressure actuated switch 172 is open, the actuating coil 174 for the relay contact 170 cannot be energized and the contact 170 remains closed. When the rotor 164 of the stepping relay is manually turned from the position shown, a circuit is completed through such rotor and the contact 170 and the primary winding 176 of a power transformer 178. A circuit is also closed through a ready pilot light 180. A normally open starting button 182 can then be depressed to complete a circuit from chassis ground through a secondary winding 184 of the transformer 178, a current limiting resistor 186, a rectifier diode 188, a normally closed stop button 190, the actuating coil 192 of a high voltage power relay and the start button 182 to chassis ground. Energization of the relay coil 192 closes the normally open relay contact 194 in parallel with the start button 182 to complete a holding circuit for the power relay coil 192. It also closes normally open relay contact 196 to complete a circuit from the 115 volt line 159 through the rotor 164 of the stepping relay and the relay contacts 170 7 to the high voltage supply 200. This lights pilot light 197 to show that the circuit is operating and such light remains on as long as power is supplied to the high volt age supply 200.

It is noted that, if the pressure switch 172 were closed, the relay coil 174 would be connected in parallel with the relay coil 192 to open the contact 170 when the start button is depressed, thus preventing the energization of the high voltage supply 200. The transformer 178 is also disconnected from the line so that the energization of the relay coils 174 and 192 fails. The result is that the contacts of these relays merely vibrate as long as the start button is held closed unless the switch 172 is opened by pressure in the module casing 26. The rectifying circuit including the diode 188 has a filter circuit made up of the capacitor 202 and resistor 204 so that the rate of vibration is relatively slow.

Upon closure of the contact 196 of the high voltage power relay, the high voltage supply 200 is connected to the 115 volt line through one of two current limiting variable resistors 206 or 208, depending upon the position of switch 209 which set the rate of charging the modules of the circuit of FIG. 13. The position of the switch is selected in accordance with whether the X-ray tube 30 is positioned in the housing in the unit itself and thus operated at maximum voltage or is operated at the end of a cable and at a lower voltage. The high voltage supply 200 may be of any conventional type capable of providing a DC. output voltage of, for example, 17 kv. with a current of a few milliamperes.

The voltage builds up across the output of the high voltage supply as the transmission lines of the modules 28 charge and a portion of this voltage is obtained through a voltage dropping circuit including a resistor 210 in series with a pair of potentiometers 212 and 214 connected in parallel and between the high voltage supply outlet and the chassis ground. Depending upon the position of a switch 216 ganged with the switch 209, a portion of the voltage referred to is applied through one of the potentiometers 212 or 214 and the switch 216 to the emitter of a unijunction transistor 218 having one of its base electrodes held at a constant positive voltage by a Zcner diode 220 connected through a resistor 222 to the output of the rectifier diode 188. The Zcner diode has its cathode connected to the resistor 222 and such base of the transistor 218 and the anode of the Zener diode is connected to chassis ground. A transient by-pass capacitor 223- is connected between the emitter of the transistor 218 and chassis ground.

The other base of the unijunction transistor is connected to chassis ground through a resistor 224 and to the gate electrode of a silicon controlled rectifier 226 having its base connected to chassis ground. The controlled rectifier has its anode connected through resistors 228 and 230 and normally closed contacts 232 to the output of rectifier diode 188. As described below, the contacts 232 are momentarily opened each time the actuating coil 168 is energized to step the relay rotor 164 one step. When the positive voltage supplied from the high voltage supply 200 to the emitter of the transistor 218 exceeds the positive voltage applied to one of the bases thereof as set by the Zener diode 220, a pulse of current is supplied to the gate electrode of the controlled rectifier through the base circuits of the. transistor 218 to cause the controlled rectifier to fire. A relatively large current flows through such controlled rectifier. A voltage is developed across the resistor 230 and the actuating coil 234 of a trigger relay connected in parallel with the resistor 230 is energized to actuate such relay. A transient by-pass capacitor 235 is connected between the anode of the controlled rectifier 226 and chassis ground. Upon energization of the coil 234 a relay contact 236 is opened to open a charging circuit for a capacitor 238. This charging circuit extends from chassis ground through the secondary transformer winding 240, a current limiting resistor 242, a rectifier diode 244, a resistor 246, the contacts 236 and the capacitor 238 to chassis ground. The charging circuit also contains a filter capacitor 248 and resistor 250. Energizing the coil 234 also closes the contacts 251 to connect the trigger output cable 96 across the capacitor 238 to provide a trigger output pulse applied to the trigger electrode 123. This occurs when the voltage output of the high voltage supply 200 reaches a predetermined voltage determined by the settings of the resistors 206 and 208 and potentiometers 212 and 214 and the positions of the switches 209 and 216 insuring that the transmission lines of the modules 28 are charged to the desired voltage.

When a trigger pulse is thus supplied to the trigger electrode 123, a triggering spark is produced between such electrode and a spark gap ball 134 of the module 29 shown in FIG. 8. This causes all of the spark gaps to fire substantially instantaneously and as a result all of the transmission lines of the modules are discharged in series through the X-ray tube 30. The voltage output of the high voltage supply falls to a low value to render the base circuits of the transistor 218 of FIG. 14 substantially nonconductive. Current flow through the gate electrode of controlled rectifier 226 becomes very low but conduction through the anode base circuit continues.

Energization of the actuating coil 234 due to such current flow through the controlled rectifier 226, however, closes contacts 252 to complete a circuit through the bridge rectifier 254. This circuit may be traced from one side of the line through the rotor 164 of the stepping relay, the relay contacts 170, the relay contacts 252 and the bridge rectifier 254 to the other side of the line. Upon completing such circuit, the rectifier supplies DC. to the coil 168 of the stepping relay, a filter capacitor 256 being provided across the output of the rectifier to smooth the current energizing the coil 168. Energization of the coil 168 momentarily opens the contacts 232 to break the circuit through the controlled rectifier 226 described above and thus restore such rectifier to non conducting condition. This deenergizes relay actuating coil 234 to open contacts 252 to deenergize coil 168 of the stepping relay and also open contacts 251 and close contacts 236 to cause capacitor 238 to be again charged.

The energization of coil 168 also steps the relay rotor 164 one step in a counterclockwise direction to count one high voltage, high current output pulse to the X-ray tube from the transmission lines of the modules 28.

The operation just described leaves the circuit in condition to again charge the transmission lines of the modules to a predetermined value at which time a trigger pulse is again sent to the trigger electrode 123 to deliver another high voltage, high current pulse to the X-ray tube 30. This continues until the rotor 164 of the stepping relay breaks the line circuit to stop the production of such pulses. At this time all of the energized relays become deenergized and all power is removed from the circuits. Operation cannot be started without manually setting the rotor 164 of the stepping relay and depressing the start button.

The stop button can be depressed at any time to stop the production of pulses but this leaves the circuit in the ready position if the stepping relay rotor 164 has not reached its open circuit position so that the pulses can be again started by depressing the start button 182 and will continue until the stepping relay rotor reaches the open circuit position. A remote start switch can be connected in parallel with the start switch 182, if desired, through a cable connector 258 shown in FIGS. 1 and 9.

It will be apparent'that operation of the device merely requires manually rotating the rotor 164 of the stepping relay clockwise in FIG. 14 through a desired angle to select the number of pulses of X-ray radiation to be produced followed by depression of the start button 182 or a remote start button connected at 258. The switches 209 and 216 are, of course, previously set to the correct position depending upon whether the X-ray* tube is mounted internally as shown in FIGS. 1 and 3, or externally as indicated in FIG. 9. Adjustment of the potentiometers 212 and 214 sets the voltages of the pulses produced for the X-ray tube employed internally and externally, respectively, and adjustment of the resistors 206 and 208, respectively, sets the time between the pulses for given settings of the potentiometers 212 and 214, thus determining the pulse repetition rates.

As an indication of the size of the unit shown in FIGS. 1 and 9, the major dimension of the carrying case may be of the order of one foot in a device where the power supplied to the X-ray tube is of the order of 150 kv. at 1400 amperes in pulses of 0.1 microsecond. This requires modules each charged to kv. and the resulting X-ray pulse has a penetration of the order of 2 inches of aluminum at one foot. The modules can be recharged in a fraction of a second so that rapidly repeating pulses of X-ray radiation can be produced, the number in a specific device depending upon the number of steps of the stepping relay rotor 164.

A modified electricity storage and X-ray tube assembly is shown in FIGS. 10 to 12, inclusive, and includes a cylindrical metal casing 260 closed at one end by a metal cap 262 welded to the casing 260 and at the other end by a closure structure 264 secured to the casing 260 by interengaging screw threads 266 on the casing 260 and on a metal cup-shaped member 268 forming part of the closure structure 264. The casing 260 is lined with insulating material 270 and also the cup-shaped member 268 is lined with similar insulating material 272. The insulating material 270 and 272 may be a synthetic resin cast in place, for example, an epoxy resin. A gasket 274 may be employed between the two linings of insulating material 270 and 272 to seal the interior of the casing assembly from the atmosphere.

A central cylindrical member 276 of insulating matrial has one end 278 screw-threaded into the insulating material 272 of the closure structure and has a bore 279 in its end 278 to receive the body portion of an X-ray tube 30 which may be of the same type as the tube 30 described with respect to FIGS. 1 and 3. The tube 30 extends through an aperture in the cup-shaped member 268 and the external flange provided by the annular member 58 of the tube is clamped between the cup-shaped member and a metallic cap member 280 secured to the cup member 268 by screws 282. The cup-shaped memher 268 has an X-ray window 284 in alignment with the end of the tube.

The central member 276 has an axially extending anode conductor 286 embedded therein into one end of which an anode connector 288 may be adjustably screw-threaded. The anode connector 288 is shown as a solid rod butit will be apparent that a spring pressed or telescopic anode connector such as shown at 80 in FIG. 3 may be employed. The other end of the anode conductor terminates in an enlarged cylindrical member 290 to which a circular corona shield 292 is secured at its center by a screw 294. The corona shield is at a high voltage with respect to the casing 260 and has a rolled edge 296 of relatively large radius of curvature.

-A plurality of electricity storage and spark gap modules 298 and a similar module 300 for also performing a triggering operation are positioned on the central member 276 and held in position by the corona shield 292. Thus the modules 298 and 300 may be installed on the central member 276 while the central member is attached to the closure structure 264 and while such closure structure is detached from the casing 260. The corona shield 292 can then be secured to the central member 276 and the casing 260 then threaded into the cup-shaped member 268 of the closure structure.

The modules 298 each include a precast annular cupshaped member 302 in which are positioned the various parts making up an artifical transmission line of substantially uniform characteristic impedance, as well as isolating inductors, spark gap elements and contact elements. Such parts are potted or cast into a body of insulating material which is shown left out of FIGS. 11 and 12 for clarity of the drawings.

Thus the modules 298 and 300 all have four connector elements 316, 318, 320 and 322 embedded therein, which correspond generally to the connector elements 116, 118, 120 and 122, respectively, of FIG. 13. The circuit of the modules 298 and 300 differ slightly from that of FIG. 13 but is equivalent as will be apparent from the following description.

The modules 298 and 300 all contain a plurality of high voltage capacitors 324, all having one terminal connected to a supporting and connector arcuate metallic plate 326 which is connected directly to the contact element 316 and through an isolating inductor 328 to the contact element 320. In the case of the modules 298 the contact element is also connected directly to one spark gap ball 330 adjustably positioned in a recess 332 in the periphery of the module. In the case of the module 300 such contact element 320 is connected to an inner conductor element 334 of a trigger spark gap ball 336 also positioned in a recess 332 of the module 300. The trigger spark gap ball has a member 338 of insulating material surrounding the conductor element 334 and such member is in turn surrounded by a conducting hollow ball element 340 leaving a short annular spark gap between the conducting elements 334 and 340. The trigger conducting element 340 has a conducting post 342 secured thereto which makes contact with a contact element 344 embedded in the insulating material 272 of the closure structure 264 and having a similarly embedded conductor 346 connected thereto. The post 342 may be hollow and may contain a spring expanded telescopic connector element 347 for insuring electrical contact between the post 342 and contact element 344.

The capacitors 324 all have their other terminals connected to intermediate points in a series of inductors 348, which with the capacitors form anartificial transmission line. One end of such series is connected through a connector element 350, which also functions as an inductor in the series, to the contact element 318. The midpoint of such series is also connected through an isolating inductor 352 to the contact element 322 which is also connected to another spark gap ball 353 adjustably supported in the recess 332. The various modules are positioned so that the contact elements 316 are adjacent the contact elements 320 and the contact elements 318 are adjacent the contact elements 322. Each of the contact elements 318 and 320 may have a telescopic spring expanded connector element 347 in their hollow interior for engagement with the contact elements 322 and 3-16.

The closure structure 264 of FIG. 10 may be similar to that shown in FIGS. 2 and 7 in that it has connectors (not shown) similar to connectors and 92 of FIGS. 2 and 7 for charging voltage and trigger voltage, respectively, the trigger connector being connected to the contact element 344 of FIG. 12 through the conductor 346 and the charging voltage connector being similarly connected to a contact element (not shown) aligned with the contact element 318 of the module 300. The trigger transformer will, however, be positioned externally of the assembly of FIG. 10.

The closure structure 264 may have a connector 353 for enabling gas such as nitrogen to be introduced into the interior of the casing 260 so that the space surrounding the modules 298 and 300 can be placed under superatmospheric pressure, for example, 20 to 30 psi. Such pressurization enables the output voltage to be increased over that which can be employed at atmospheric pressure and also allows the output voltage to be varied by varying the pressure to thereby vary the breakdown voltage of the spark gaps without requiring mechanical adjustment of the length of the spark gaps. When the nitrogen gas in the spark gap between the trigger ball 3 36 and ball 353 is ionized, it emits ultra-violet light which results in a more rapid ionization of the remaining spark gaps and causes the output voltage pulse applied to the X-ray tube to have a shorter rise time and a narrower width. It also prevents entrance of moisture, dust, etc., from the atmosphere so as to largely eliminate any effects of the atmosphere upon the operation of the device.

The cover cap 280 of FIG. 10 may have a connector 354 for introducing gas, such as Freon, under pressure into the bore 279 containing the X-ray tube 30 and the flange provided by the annular member 58 of the X-ray tube may be suitably perforated to enable the gas to enter the rear portion of the bore. The employment of gas under pressure, for example, 1 psi. around the X-ray tube eliminates atmospheric effects in the same manner that pressure in the interior of the casing 260 eliminates such effects.

The casing 260, closure structure 264 and cover cap 280 of FIG. 10, provide a completely closed grounded 1 metal enclosure for the high voltage pulse circuitry and the X-ray tube of the modification of FIGS. 10 to 12, thereby providing operator safety and minimizing radio frequency noise generation due to high current-high voltage pulse discharges. It will be appreciated that the interior of the bore or chamber surrounding the X-ray tube in all of the modifications will be lined with a layer of lead (not shown) in accordance with standard practice to provide X-ray shielding except in the direction of desired X-ray propagation. 4

The assembly of FIGS. 10 to 12 will be operated with a suitable control and charging circuit which may besimilar to that of FIG. 14. The assembly may be constructed in various sizes for operation at various high voltages and currents as well as various pulse lengths, and the same is true of the assembly of FIGS. 2, 3 and to 7. In any event, the invention results in an extremely compact and lightweight structure as compared with prior structures for accomplishing anything approaching the effectiveness of the present X-ray unit.

It should be apparent, however, that the invention is not limited to the details disclosed but that many other modifications are possible.

We claim:

1. A device for producing high voltage, high current pulses comprising:

a plurality of similar storage modules of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance and capable of being charged to a high voltage, v

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors positioned on said sides having said major surfaces to connect the transmission line sections of said modules for charg ing said sections in parallel,

means including at least two spark gap electrodes attached to each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series to discharge said sections when said spark gaps break I down and to produce a high voltage, high current pulse,

an ionizable gas in said spark gaps, and

means for generating light and causing said light to be transmitted along said light path through the gas in the spark gaps to enable all of said spark gaps to break down at substantially the same time.

2. A device for producing high voltage, high current pulses comprising:

a plurality of similar storage modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially' the same uniform characteristic impedance capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors at least partly embedded in said sides having said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

means including isolating inductors embedded in each of said modules and spark gap electrodes secured to each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series to discharge said sections when said spark gaps break down and to produce a high voltage, high current pulse,

an ionizable gas in said spark gaps, and

means for causing one of the spark gaps to break down and to emit light from the ionized gas in said one gap and for transmitting said light along said light path through the remaining spark gaps to enable all of said spark gaps to break down at substantially the same time.

3. A device for producing high voltage, high current pulses comprising:

a casing,

a plurality of similar storage modules of solid insulating material positioned in said casing,

each of said modules containing a section of artificial transmission line of substantially the same uniform characteristic impedance formed by a plurality of separate inductors and capacitors and capable of being charged to a high voltage,

connection means carried by said modules providing for charging the transmission line sections of said modules in parallel,

means including a plurality of spark gap electrodes connected to the transmission line sections for d'ischarging said transmission line sections in series,

said spark gap electrodes being positioned on said modules to form a plurality of spark gaps so that said spark gaps are exposed to each other in a common light path,

a filling of gas within said casing with a portion of said gas in said spark gaps, and

means for causing at least one of the spark gaps to break down and ultraviolet light to be emitted from the ionized gas in said one gap and for transmitting said light through the remaining spark gaps to cause all of said spark gaps to break down at substantially the same time.

4. A device for producing high voltage, high current pulses comprising:

a plurality of similar modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each contain ing a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

means for holding modules in alignment with the major surfaces of adjacent modules in contact with each other,

connection means including connectors embedded in said sides having said major surfaces to connect the transmission line sections of said modules together for charging said sections in parallel,

means including a pair of spark gap electrodes positioned on each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series when said spark gaps break down to supply a high voltage, high current pulse, an ionizable gas in said spark gaps, and

'13 means for generating light and transmitting said light along said light path through said spark gaps to ionize said gas and to cause all of said spark gaps to break down at substantially the same time. 5. A device for producing high voltage, high current pulses comprising:

a plurality of similar modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of artificial transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

means including a casing for holding said modules in alignment with said major surfaces adjacent each other,

charging means including connectors embedded in said sides having said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

discharging means including at least two spark gap electrodes positioned in a recess in each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series to discharge said sections when the spark gaps break down and to produce a high voltage, high current pulse,

each of said modules being substantially rectangular in shape and having said recess in one side edge thereof,

said casing having a rectangular interior fitting said modules and an end closure structure containing electrical connections to one of said modules,

an ionizable gas in said spark gaps, and

' means for causingione of the spark gaps to break down and to emit ultraviolet light from the ionized gas in said one gap and for transmitting said ultraviolet light along said light path through all of the remain ing spark gaps to enable all of said spark gaps to break down at substantially the same time.

6. A device for producing high current, high voltage pulses comprising:

a plurality of modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance embedded in insulating material and capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces each other,

charging means including connectors carried on said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

discharging means including at least two spark gap electrode-s positioned on each of said modules to form a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series to discharge said sections when said spark gaps break down and to produce a high voltage, high current pulse,

an ionizable gas in said spark gaps, and

means including a trigger electrode in one of said spark gaps for triggering the break down of said one spark gap to emit ultraviolet light from the ionized gas of said one gap and for transmitting said light through the remaining spark gaps to cause all of said spark gaps to break down at substantially the same time.

7. A device for producing rectangular high voltage,

high current pulses comprising:

a plurality of similar modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors carried by said sides having said major surfaces for connecting the transmission line sections of said modules for charging said sections in parallel,

means including at least two spark gap electrodes secured to each of said modules to provide a plurality of spark gaps between the transmission line sections for connecting said transmission line sections in series when the spark gaps break down to discharge said sections and to produce a rectangular high voltage, high current output pulse,

charging means connected to said unit for charging said transmission line sections to the same predetermined DZC. voltage,

an ionizable gas in said spark plugs,

means for applying a triggering pulse to cause the break down of one said spark gaps to emit light from the ionized gas of said one spark gap and for transmittin'g said light through the remaining spark gaps to cause all of said spark gaps to break down at substantially the same time to produce said output pulse,

and control means for causing a series of said triggering pulses'to be produced by said triggering means and for causing the charging means to completely recharge the transmission linesections between sucacteristic impedance and capable of being charged to a high voltage, means for holding said modules in alignment with said tmajo'r surfaces adjacent each other,

connection means including connectors positioned in said sides having said major surfaces to connect said transmission line sections of said modules for charging said sections in parallel,

a diode X-ray tube, having an anode and a field emission cathode structure including a plurality of spaced sharpened emitting elements directed toward said anode,

means including at least two electrodes attached to each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission. line sections in series with said X-ray tube to discharge said sections When said spark gaps break down and to supply a rectangular high voltage, high current pulse to said tube,

an ionizable gas in said spark gaps, and

means for generating light and causing said light to be transmitted along said light path through said spark gaps to enable said spark gaps to break down at substantially the same time.

9. An X-ray unit comprising:

a plurality of similar modules of solid insulating material and of generally plate-like sliape halving opposed major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance formed by a plurality of separate inductors and capacitors and capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connecting means including connectors positioned in said sides having said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

an X-ray tube having an anode and a field emission cathode structure including a plurality of spaced sharpened emitting elements directed toward the anode,

means including at least two spark gap electrodes positioned in a recess in each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series with said X-ray tube to discharge said sections when said sparkgaps break down and to supply a rectangular high voltage, high current pulse to said tube,

an ionizable gas in said spark gaps,.

means for causing one of the spark gaps to break down to emit light from the ionized gas in said one gap through the remaining spark gaps to cause all of said spark gaps to break down at substantially the same time to provide said rectangular pulse with a short rise time,

each of said modules being substantially rectangular in shape and having said recess in'one side edge thereof,

said means for holding said modules in alignment including a casing for said modules with a rectangular interior fitting said modules,

said casing having means for housing said X-ray tube.

10. An X-r-ay unit comprising:

a casing,

a plurality of similar modules of solid insulating material positioned in said casing and stacked in contact with each other,

each of said modules containing a section of transmission line of substantially the same uniform characteristic impedance embedded in said insulating material and capable of being charged to a high voltage,

connection means carried by said modules providing for charging the transmission line section of said modules in parallel,

an X-ray tube having an anode and a field emission cathode structure including a plurality of pointed emitting elements directed toward said anode,

means including spark gap electrodes attached to said modules for discharging said transmission line sections in series through said X-ray tube to apply a rectangular output pulse of high voltage and current across the anode and cathode of the X-ray tube,

said spark gap electrodes being positioned on said modules to form a plurality of spark gaps so that said spark gaps are exposed to each other along a common light path,

a filling of gas within said casing to provide a portion of said gas in said spark gaps, and

means for causing at least one of the spark gaps to break down and to emit ultraviolet light from the ionized gas in said one gap and for transmitting said light through the remaining spark gaps to cause said spark gaps to break down at substantially the same time and to provide said rectangular output pulse 'with a short rise time and narrow width.

11. -An X-ray unit comprising a casing having an elongated rectangular interior,

a plurality of modules positioned within said casing and each including a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

;an elongated X-ray tube having an anode and a field 15 for transmission of X-rays from said tube to the exterior of said housing,

charge means including connectors carried by said modules providing for charging the transmission line sections of said modules in parallel to said high voltage,

discharge means for discharging said transmission line sections in series through saidtube to apply a rectangular pulse of high voltage and current across the anode and cathode of the tube to generate an intense pulse of X-rays,

said discharge means including a pair of spark gap electrodes carried by eachof said modules and positioned in a recess in said module to provide a plurality of spark gaps for connecting the transmission line sections together,

said modules being positioned in said casing with said recesses in alignment and the spark gaps of said modules exposed to each other in a common light path,

said modules being rectangular and fitting said interior of said casing,

an ionizable gas in said spark gaps, and

means for generating ultraviolet light and transmitting said ultraviolet light along said light path through said spark gaps to cause said spark gaps to break down at substantially the same time.

12. An X-ray unit comprising:

a casing having a circular cylindrical interior,

a plurality of modules positioned within said casing and each including a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

an elongated X-ray tube having a field emission cathode with a plurality of spaced pointed elements and an anode,

said casing having a housing portion for receiving and housing'said X-ray tube and providing a window for transmission of X-rays from said tube to the exterior of said housing, 1

charge means carried by said modules for charging the transmission line sections of said modules in parallel to said high voltage,

discharge means for discharging said transmission line sections in series through said tube to apply a rectangular pulse of high voltage and current across the anode of the cathode of the tube to generate an intense pulse of X-rays, Y

said discharge means including at least two spark gap electrodes carried by each of said modules and positioned in a recess in,an edge of said module, to provide a plurality of spark gaps for connecting the transmission line sections together,

said modules being positioned in said casing with said recesses in alignment and said spark gaps exposed to each other in a common light path,

said modules being annular and fitting said interior of said casing,

said casing having a central member extending through said modules and providing said housing for said tube, 7

an ionizable gas in said spark gaps, and

means for causing one of the spark gaps to break down to emit light from the ionized gas in said one gap and for transmitting said light through all-the remaining gaps to cause said gaps to break down at substantially the same time.

13. An X-ray unit comprising:

a plurality of modules of solid insulating material of generally plate-like shape having major surfaces, on opposite sides thereof and each containing a section of transmission line of substantially the same uni: form characteristic impedance capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors positioned on said sides having said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

an X-ray tube having a conical anode and a field emission cathode structure including a plurality of needle elements positioned about said anode and directed radially inward toward said anode,

means including at least two spark gap electrodes attached to each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series with said X-ray tube to supply a rectangular high voltage, high current pulse to said tube,

an ionizable gas in said spark gaps,

charging means connected to said unit for charging said transmission line sections to said high voltage,

and triggering means including a trigger electrode in one of the spark gaps for triggering the break down of said one gap to emit ultraviolet light from the ionized gas of said one gap through the remaining spark gaps .to cause said spark gaps to break down at substantially the same time and to provide said rectangular pulse with a short rise time.

14. An X-ray unit comprising:

a plurality of similar modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors positioned on said sides having said major surfaces to connect the transmission line sections of said modules for charging said section in parallel,

an X-ray tube having an anode and a field emission cathode structure including a plurality of needles directed toward said anode,

means including at least two spark gap electrodes attached to each of said modules to provide a plurality of spark gaps in a common light path and between the transmission line sections for connecting said transmission line sections in series with said X-ray tube to supply a rectangular high voltage, high current output pulse to said tube,

an ionizable gas in said spark gaps,

charging means connected to said unit for charging said transmission line sections to said high voltage,

triggering means for applying a triggering voltage pulse to one ofsaid spark gaps to cause said one gap to break down and to emit ultra violet light from said one gap through one of the remaining spark gaps to cause said spark gaps to break down at substantially the same time,

and control means for causing a series of said trigger pulses to be produced by said triggering means, and for causing the charging means to recharge the transmission line sections between successive triggering pulses,

said control means including means for presetting and varying the number of said triggering pulses in each of said series to produce a corresponding number of output pulses.

15. An X-ray unit comprising:

a plurality .of similar modules of solid insulating material and of generally plate-like shape having major surfaces on opposite sides thereof and each containing a section of transmission line of substantially the same uniform characteristic impedance capable of being charged to a 'high voltage,

means for holding said modules in alignment with said major surfaces adjacent each other,

connection means including connectors positioned on said sides having said major surfaces to connect the transmission line sections of said modules for charging said sections in parallel,

an X-ray tube having an anode and a field emission cathode structure including a plurality of spaced pointed emitting elements,

means including at least two spark gap electrodes positioned in a recess in each of said modules to provide a plurality of spark gaps positioned in a common light path for connecting said transmission line sections in series with said X-ray tube to supply a high voltage, high current output pulse to said tube,

an ionizable gas in said spark gaps,

charging means connected to said unit for charging said transmission line sections to said high voltage,

and triggering means for applying a trigger voltage pulse to a trigger electrode in one of said spark gaps to cause said one gap to break down and the ionized gas in said one gap to emit light to all of the remaining spark gaps to cause said gaps to break down at substantially the same time,

and control means for causing a series of said trigger pulses to be produced by said triggering means, and for causing the charging means to recharge the transmission line sections between successive trigger pulses,

said control means including means for presetting and varying the number of said trigger pulses in said series to produce a corresponding number of output pulses,

and including means responsive to a predetermined voltage to which said transmission line sections are charged for initiating the operation of said triggermg means.

References Cited by the Examiner UNITED STATES PATENTS 1,734,917 11/1929 Peek 25093X 2,129,646 9/1938 Bouwers 250-98 X 2,230,176 1/1941 Bouwers et a1. 250-87 2,447,832 8/1948 Abend etal 250-98X 2,524,240 10/1950 Titterton et a1. 250-98 2,534,758 12/1950 Titterton 25098 2,578,263 12/1951 Perkins 320-1 3,059,165 10/1962 Meykar 321-15 FOREIGN PATENTS 150,238 2/1953 Australia. 389,813 3/1933 Great Britain. 407,837 3/1934 Great Britain.

RALPH G. NILSON, Primary Examiner. 

1. A DEVICE FOR PRODUCING HIGH VOLTAGE, HIGH CURRENT PULSES COMPRISING: A PLURALTIY OF SIMILAR STORAGE MODULES OF GENERALLY PLATE-LIKE SHAPE HAVING MAJOR SURFACES ON OPPOSITE SIDES THEREOF AND EACH CONTAINING A SECTION OF TRANSMISSION LINE OF SUBSTANTIALLY THE SAME UNIFORM CHARACTERISTIC IMPEDANCE AND CAPABLE OF BEING CHARGED TO A HIGH VOLTAGE, MEANS FOR HOLDING SAID MODULES IN ALIGNMENT WITH SAID MAJOR SURFACES ADJACENT EACH OTHER, CONNECTION MEANS INCLUDING CONNECTORS POSITIONED ON SAID SIDES HAVING SAID MAJOR SURFACES TO CONNECT THE TRANSMISSION LINE SECTIONS OF SAID MODULES FOR CHARGING SAID SECTIONS IN PARALLEL, MEANS INCLUDING AT LEAST TWO SPARL GAP ELECTRODES ATTACHED TO EACH OF SAID MODULES TO PROVIDE A PLURALITY OF SPARK GAPS POSITIONED IN A COMMON LIGHT PATH FOR CONNECTING SAID TRANSMISSION LINE SECTIONS IN SERIES TO DISCHARGE SAID SECTIONS WHEN SAID SPARK GAPS BREAK DOWN TO PRODUCE A HIGH VOLTAGE, HIGH CURRENT PULSE, AN IONIZABLE GAS IN SAID SPARK GAPS, AND MEANS FOR GENERATING LIGHT AND CAUSING SAID LIGHT TO BE TRANSMITTED ALONG SAID LIGHT PATH THROUGHT THE GAS IN THE SPARK GAPS TO ENABLE ALL OF SAID SPARK GAPS TO BREAK DOWN AT SUBSTANTIALLY THE SAME TIME.
 8. AN X-RAY UNIT COMPRISING: A PLURALITY OF SIMILAR MODULES OF GENERALLY PLATE-LIKE SHAPE HAVING MAJOR SURFACES ON OPPOSITE SIDES THEREOF AND EACH CONTAINING A SECTION OF TRANSMISSION LINE HAVING SUBSTANTIALLY THE SAME UNIFORM CHARACTERISTIC IMPEDANCE AND CAPABLE OF BEING CHARGED TO A HIGH VOLTAGE, MEANS FOR HOLDING SAID MODULES IN ALIGNMENT WITH SAID MAJOR SURFACES ADJACENT EACH OTHER, CONNECTION MEANS INCLUDING CONNECTORS POSITIONED IN SAID SIDES HAVING SAID MAJOR SURFACES TO CONNECT SAID TRANSMISSION LINE SECTIONS OF SAID MODULES FOR CHARGING SAID SECTIONS IN PARALLEL, A DIODE X-RAY TUBE, HAVING AN ANODE AND A FIELD EMSISION CATHODE STRUCTURE INCLUDING A PLURALITY OF SPACED SHARPENED EMITTING ELEMENTS DIRECTED TOWARD SAID ANODE, MEANS INCLUDING AT LEAST TWO ELECTRODES ATTACHED TO EACH OF SAID MODULES TO PROVIDE A PLURALTIY OF SPARK GAPS POSITIONED IN A COMMON LIGHT PATH FOR CONNECTING SAID TRANSMISSION LINE SECTIONS IN SERIES WITH SAID X-RAY TUBE TO DISCHARGE SAID SECTIONS WHEN SAID SPARK GAPS BREAK DOWN AND TO SUPPLY A RECTANGULAR HIGH VOLTAGE, HIGH CURRENT PULSE TO SAID TUBE, AN IONIZABLE GAS IN SAID SPARK GAPS, AND MEANS FOR GENERATING LIGHT AND CAUSING SAID LIGHT OT BE TRANSMITTED ALONG SAID LIGHT PATH THROUGH SAID SPARKS GAPS TO ENABLE SAID SPARK GAPS TO BREAK DOWN AT SUBSTANTIALLY THE SAME TIME. 